Tag Archives: environmental stress

A salty tale of life on the road

Dipsacus fullonum In the UK, when it snows we panic. Over two million tonnes of salt are spread onto the UK roads each year. At the same time, roadside verges are rapidly becoming life-giving arteries in the countryside, linking habitats and acting as vital corridors for wildlife to thrive on. They also represent a remnant of our native grassland which has suffered catastrophic losses over the last century (Plantlife Read Verge Campaign). Apart from a few seaside species, wild flowers don’t like salt – not even a teaspoonful, let alone two million tonnes a year.

Teasels are an important species for wildlife, visited by bees when they are in flower and birds when carrying seed. The brown seeds from the spiny flower-head of the teasel is a favourite food of goldfinches in winter. And teasels don’t like salt. Writing in AoB PLANTS, Beaton and Dudley examine the salt tolerance observed in roadside populations of the common teasel (Dipsacus fullonum L. subsp. sylvestris) and discuss how this plant responds to new and challenging environments.

Beaton, L.L., and Dudley, S.A. (2013) Tolerance of roadside and oldfield populations of Dipsacus fullonum subsp. sylvestris (Dipsacaceae) to salt and low osmotic potentials during germination. AoB Plants. 5: plt001 doi: 10.1093/aobpla/plt001
Plants inhabiting degraded habitats must contend with stressful environments. However, their ability to adapt may be constrained by available genetic variation and genetic correlations between traits. Here, we examine the correlation between salt and drought tolerance in germinating seeds from contrasting populations of common teasel (Dipsacus fullonum subsp. sylvestris) growing on roadsides that experience high salinity due to de-icing salts, or growing in an old field site, remote from roadsides and free of salinity stress. We examined the contribution of drought and salinity tolerance to the tolerance of roadside conditions in seedlings from five maternal families from three roadside and three old field populations. Germination and early growth were compared under high salinity, low water potential set at −0.5 MPa with solutions of polyethylene glycol 8000, sodium chloride or vermiculite wetted to −0.5 MPa with distilled water. Root length and the emergence of cotyledons (where appropriate) were used as a measure of performance. Maternal families from roadside populations displayed greater tolerance of both high salinity and drought than families from old field populations. However, no maternal family possessed tolerance to both drought and salinity. Salt and drought tolerance during germination were not correlated, indicating that they are separate traits in this species.

 

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Cadmium and hypodermal periderm formation in roots

Cadmium and hypodermal periderm formation in roots
Cadmium and hypodermal periderm formation in roots

Periderm as a result of secondary meristem activity is not usually formed in monocot species. Lux et al.  describe periclinal cell division in the hypodermal layer of Merwilla plumbea, an African medicinal species often found on contaminated soils, which results in formation of multilayered suberized tissue when roots are treated with cadmium. This may be a novel defence reaction of young plants, protecting the roots from radial uptake of Cd ions.

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